<!DOCTYPE html>
<html>
	<head>
		<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
		<title>三行一列布局</title>
	</head>
	<body>
		<!--页头 -->
		<header></header>
		<!--主体内容 -->
		<section></section>
		<!--页脚 -->
		<footer></footer>
	</body>
</html>
